houskeeper



Aug. 21, 1923. 1,465,394

w. G. HOUSKEEPER CONTROL APPARATUS FOR EVACUATED VESSELS- Filed Nov. 6, 1920 #H IU I I l Patented Aug. 21', 1923.

PATENT QFFECE.

WILLIAM G. HOUSKEEPER, OF NEW $593K, It. 34".,

CONTROL APPARATUS 1" Application filed November F at New York, in the county ot New I: ind State oi. .h'ew .i'lz, have invented certain new and uscitui improvements in Ceiiitrol ilipparatus for Evacuated Vessels, of which the following; is a full, clear, concise and exact description.

This invention relates to control apparatus for evacuated vessels. More particularly, it relates to means and methods to: ci'mtrolling the intensity oi"; ifiillf iiltlfill with- :iii. an evacuated vessel.

It well known that vacuuu'i tubes of the electron discharge type are provided with a heated cathoi'le which serves as the source electrons. As described the elnited States patent to Buckley, No. il,2-5Til,i'98, patented lli'iarch 29, 19%, such atube may he used as a vacuum gauge, the ionization of the being a ia'icasure of the gas pressure. has been discovered that fluctuations in the gas pressure within the vacuum tube give corresponding fluctuations in. the intensity oi:- the electron discharge from heated lilament. For some gases as oxygen for ere ample the thermionic activity of the filament varies iuversely with changes in the pressure; tor other gases, such as liydrogeu the thermionic activity varies directly with the pressure. These fluctuations in the intens ,y elf elfl'itron discharge from the heated lilruuimt are objectionable, and in the case of the vacuum gauge lead to inaccurate resulls in measuring the pressure.

An object of: the present invention is to prevent the variations in pressure from producing fluctuations in the intensity oil the electron discharge from the heated cathode and toiusurc that the intensit oil? the anode cathode current shall be constant over a wide range of gas pressures. This is preferably accomplished by having the electron or space current in the vessel operate a translating device, which, in turn, controls, in a suitable manner, the amount of cu rent supplied to the filament or cathode. For example, the translating device may comprise a relay responsive to changes in the space current of the tube for short circuiting the filament at such a rate that the average current supplied to the filament. for heating the some is of such value as to produce the constant space current desired.

TOE VTESTEEN ELECTRIC SIGN OF NEW YORK.

serial No. 422,260.

This invention will he better understood. hy i'e'li'ereuce to the following detailed desci onion taken in connection with the accompauying ilrawing which shows, in connection with a vessel to be evacuated, an ionization inauoiueter the action ot vhich is regulated inaccordauce with this inven tion.

Referring to the drawing, 4; and 5 rcpresent vessels, pressure in which is to be u'ieasureil. I; connecting tube 6 extends from these vessels to a vessel '1 in which there are enclos d a source of electrons 8 and an electrode 9 sewing as an anode. Connected between electrodes 8 and 9 is a resistance element ii) supplied. with current from a haty ll. in such a manner that the RI drop in isistauce it), produces the desired potential is a perfect 'acuuu'i, the space current between the members 8 and 9 will he a pure electron current, the only source oi? carriers being the cathode S. inasmuch as the negatively charged electrons 'tlOlil the element 8 can pass only to an GlG(flJ} )(lG which is at :1. hi gher potential, it will. be apparent that no cur rent can flow to it from. the third electrode .ii-l. ll", hmvever, there is present a small amount oi" gas and the ill. drop across resistauce ll) sullicieutly high. the electrons will a cquir. sullicicnt velocity to ionize some of the gas molecules and there will. be Dresout hoth negative and positive ions. The positive ions will. ravel to negatively chargeiil electrodes and chiefly to that one which is at the lowest potential, that is, to the electrode .13. The collection of positive charges on this electrode will give rise eX- teriiially to a ciu'rent from this electrode to the cathode, ilili' the presence oi this cur rem; i'uay he iletected by the insertion of any suitable current measuring instrigunent, such as a galvanometer 15. Since, for a given setting of the system, the amount of this current will be proportional to the pressure, the deflection of the instrument 15 will be an indication of the degree of evacuation present in the vessel.

In the calibration of such a device it has been found convenient to calibrate for constant space current in the manometer. It is thcrefm'e, desirable when measuring"pres sure by means of this gauge, that the space current should be maintained at this value, which as has been pointed out, would require frequent adjustment with changes in pressure. in accordance with this invention, automatic means is provided for maintaining the space current at a desired value. The preferred way of accomplishing this, as shown in the accompanying drawing, consists in having the anode-cathode current pass through a relay 19 which controls the short circuit between the terminals 20, 21 of filament S. The armature 2; of relay19 is normally out of contact with point 24: so that heating currci'it is supplied to the filament. When the current flowing through the relay i9 is sullicient to cause its armature to be attracted, a short circuit around the terminals of cathode b is made, so that practically no heating current is supplied to cathode 8 while armature 22 is in contact with point 'lhis short circuitii'ig of the cathode, of course, permits the cathode to cool thereby decreasing the anode-cathode current, until the anoiile-cathode current has been decreased to such a value as to permit armature 22 to move back to its position. In the operation of the device, relay 19 is so adjusted that the cathode 8 is short circuited at such a rate that the average temperature of the cathode is sullicient to maintain the desired constant alue of the anode-cathode current. The emmections from battery 11 to cathode 8 should also be so adjusted that when cathode 8 is not short circuited the heating current will be so large as to furnish at least the desired anode current whatever the pressure of the gas in the vessel.

If desired, a suitable current measuring instrument, such as a milliammeter 27 may be inserted in the circuit between the anode 9 and the cathode S in order that the anodecat-hode current may be observed. The absolute value of this current may be determined initially, by suitable adjustments of relay 19. The tension. of the spring (not shown) for the movable contact may be varied for example in order to make the usual preliminary adjustment.

If the current supplied to cathode 8, when it is not short circuited, is suflicient to give the desired space current even when the tube is evacuated to the greatest possible extent, the device 15 has been found, in one particular case, to furnish qualitative indication of the pressure from a pressure of about .25 mm. of HGdown to about .0353 mm. of HG, while it furnishes a strictly accurate indication of the pressure from mni. down to the lowest pressure obtainable. For any pressure up to .035 mm, the temperature required by the cathode will be intermediate its temperature when short circuited and its temperature with maximum heating current. The regulating means of this invention furthermore allows the manometer to be put in operation when the tube is at atmospheric pressure and maintained. in condition for operation without any manual adjustments during the process of evacuating the tube to the lowest pressure obtainable. I

it is obvious that various modifications may be made in the structure of the system above described, without departing, in any wise, from the spirit of the invention as set forth in the appended claims.

What is claimed is:

1. The combination of a vacuum tube sulr ject to ditl'erent degrees of vacuum, a cathode in said tube, means for producing an electron streanr from said cathode, and means comprising a short circuit for said cathode and responsive to a change in the degree of the vacuum of said tube for regulating the intensity of said stream while permitting the degree of vacuum of said tube to remain substantially constant during the regulation of said stream.

2. The combination of a vessel containing a. plurality of electrodes, means for causing one of said electrodes to emit electrons, and means responsive to changes in the pressure of said vessel for intermittently short-circuiting said cathode whereby the emission from said cathode is regulated by the pres sure in said vessel while still permitting the degree of vacuum of said vessel to remain substantially constant during the regulation of said emission.

3. A vessel containing a plurality of electrodes, one of which is a cathode, another of which is an anode, means for establishing a space current between said anode and cathode, means for supplying heating current to said cathode, and means connected in circuit between said anode and cathode and responsive to current changes produced by variations in the pressure within said vessel for intermittently reducing the heatingcurrent through said cathode substantially to zero. r

4. A vessel containing a plurality of elec trodes, means for causing one of said electrodes to emit electrons, means for controlling the rate of emission of electrons from said source in accordance with the pressure within said vessel,'said second means comprising a translating device whose operation is dependent upon the rate of electron emission, and a short circuit for said cathode and controlled by said translating device for regulating said iirst mentioned means.

5. A vessel containing a plurality o1" electrodes, one of which is a cathode and another an anode, means for supplying space current between said anode and said cathode, means for supplying heating current to said cathode, and means "for causing the illtensity oi said space current to be practically .independent of changes in the pressure of said vessel over a wide range, said n'ieans comprising means connected between said anode and cathode and responsive to changes in the space current produced by pressure variations for intermittently reducing substantially to Zero the heating current upplied to said cathode.

6. A vessel containing a plurality of electrodes, a source of current for heating one of said electrodes, whereby said electrode is made a source of electrons, connections for shunting said cathode by a path of lower resistance than said cathode, and means for intermittently varying said connections whereby the electron emission from said elc 'ode is made practically independent 01 changes in the pressure in said vessel.

7. 'i.he combination of a vessel subject to different degrees of vacuum, means for supplying said vessel with an electron stream, and a relay responsive to the degree of vacuum in said vessel for intermittently temling to reduce said electron stream to zero .in response to changes in the degree of vacuum oi? said vessel.

S. The combination oi a vessel subject to different degrees oil vacuum, an electron discharge tube associated therewith, connections for removing gas "from said vessel, said tube having a cathooe and an anode, and means for intermittently short-circuiting said cathode in response to the degree of vacuum of said vessel.

9. A tube containing an anode and a cathode, means for establishing space current between said anode and cathode, a vessel adapted to be evacuated and associated with said tube, a relay whose operation is controlled by said space current, and connections controlled by said relay for intermittently short-circuiting said cathode whereby the space current in said tube is made practically independent oi the pressure in said vessel.

10. A vessel subjected to different degrees of vacuum and comprising an anode and a cathode, and means for short-circuiting said. cathode in response to variations in said pressure.

11.111 combination, a vessel subject to different degree of pressure, and comprising an anode and a cathode, and means responsive to the pressureot said vessel for short-circuiting said cathode when said pressure exceeds a predetermined value.

12. In combination, a vessel. to be evacuated, a vacuum tube subject to the same pressure variations as said vessel, and comprising an anode and a cathode, means for measuring the relative amount oi positive ionization in said tube whereby the pressure in said vessel. may be determined, means for supplying space current between anode and cathode, and means responsive to pressure changes in said tube for intermittently short-circuiting said cathode whereby said pace current may be made substantially independent of said pressure variations 13. An electric discharge device subject to variations in an operating characteristic thereof and comprising an anode and a cathode, and means for short-circuiting said cathode in response to variations in an op erating characteristic of said device.

In witness whereof, I hereunto subscribe my name this 1st day of November, A.' D. 1920.

WILLIAM G. HOUSKEEKER. 

